This article, from Cassier's Magazine, October 1898, describes the
Glasgow District Subway, a cable-operated subway.

Although regulated by the Board of Trade as a railway, it is simply
an underground system of cable tramways. It is all underground, save at
a few of the stations, and it is worked entirely by cables driven from
one power station. It is a tubular railway in two circles, the cars
running in opposite directions through two separate but parallel
tunnels. Thus, two ropes are required, one for each tunnel, on the inner
track and outer track, respectively. The whole distance around the
circle is 6 1/2 miles, and for each circle about seven miles of wire cable
are wound on to the pay-out drums.

The route is within the most populous and most actively employed
areas of the city, and in the completion of the circle the river Clyde
has to be dived under twice. As a system of street traffic the line
traverses at several points three other systems of city and suburban
lines of communication, with which it comes more or less into
competition, viz., the street tramways system of the Corporation of
Glasgow and the circular underground railways of the North British and
Caledonian Railway companies. Yet it serves portions of the city not
served by either of these systems, and it affords a valuable connecting
link between these other systems. While, like Hal o' the Wynd, fighting
for its "ain hand," the Glasgow District Subway also acts as a feeder to
its competitors.

One distinct advantage of the subway is that it relieves the
congestion of the street traffic without rendering the streets
unsightly, as an elevated railway does; and another advantage is, that
while it conveys passengers under the streets, it does not stifle them
with sulphurous fumes, as an underground steam railway does. Still a
further advantage is, that by running in separate tunnels, with fixed
stations, the subway can convey its passengers at a speed twice as great
as that possible with cars of street tramways, even when these have
mechanical traction.

The design of the Glasgow Subway is about a dozen years old, although
the system has been open for traffic only since the beginning of 1897.
The credit of the inception of the scheme belongs to Mr. Alexander
Simpson, C. E., of Glasgow, whose firm, Messrs. Simpson & Wilson, have
been throughout, and still are, the engineers of the enterprise.
Naturally, as in all great works, there has been much departure from the
original design. Mr. Simpson's first idea was for an underground cable
railway, of something under three miles, between the centre of Glasgow
and the adjoining burgh of Partick, -- in one tunnel only, with two sets
of rails. On this plan the stations were to be equidistant, and the
cars, attached to an endless chain, were to start and stop
simultaneously. The engineman at the power station would alone have
control over the two sets of trains, and would let out the requisite
length of rope when he received signals from all the stations.

This idea was ingenious (though one can now see many objections to
it), and it received the approval of the House of Lords; but the bill
was thrown out by the House of Commons, in 1887. Next year the scheme
took a larger form and another shape, appearing in a plan for a double
line in two tunnels to connect the north and south sides of the river,
as well as the districts of the previous proposal.

The Clyde Trust opposed this scheme as both invading their domain and
as calculated to prevent, or obstruct, the future deepening of the
river. Their opposition was successful, and the subway design was
suspended until another undertaking was carried through Parliament,
viz., one for a tunnel under the Clyde for pedestrian traffic. After
this had established a sort of right-of-way precedent, the subway scheme
was again sent up to Parliament, and in 1890 it was sanctioned, in spite
of the opposition of the Caledonian Railway Company, then busy with the
construction of their city and suburban underground line.

The subway line was completed in 1896 and opened for traffic in
January, 1897. Under the act the Glasgow District Subway Company
acquired the right, or free way-leave, to pass under, and follow, the
lines of streets. But the circular design necessitated the passing
under much private property, the owners of which were, or professed to
be, alarmed at the prospective effect of the tunneling on their
buildings. The company, therefore, had to purchase large blocks
of property, which may, and undoubtedly will, ultimately yield a
good return as an investement, but which have weighted the undertaking
with a much larger capital than was necessary for
the actual construction and equipment of the subway.

As an underground railway the subway is not remarkably deep. It is
true that at one place, Hillhead, the distance from the street surface
to the top of the tunnels is 115 feet, but that is because the line at
that point passes under a considerable mound. At another place the depth
is only 7 feet, and at one point in the centre of the city the depth is
40 feet. Averages in such circumstances do not mean much, but the
average depth for the whole length of the tunnels is 29 feet from the
street surface.

The tunnels are practically two endless cylindrical tubes, at slightly
varying distances apart, but opening out together at each station into
one large arch of 28 feet span. At suitable intervals along the tunnels
are openings through which the surfacement may pass from one line to the
other without returning to a station. The general curvature is very
considerable, yet the sharpest curve on the line is of not more than
660 feet radius. The gradients while easy for cable traction, would be
regarded steep for steam or electric power, -- those where the tunnels
pass under the Clyde being 1 in 18 and 1 in 20, respectively.

The tunnels were formed for the most part on what is caled the "cut
and cover" method. Where brick-clay was encountered, ordinary brick
tunneling was used. In passing under important blocks of buildings and
factories, the work was done by iron tunneling, sometimes with, and
sometimes without, the use of compressed air. In working beneath the
river the tunnels were driven under air-pressure, with such effect that
the river bed was blown up about a dozen times before the crossing was
completed. The cross-river tunnels are remarkable triumphs of
constructive engineering under extremely difficult conditions. It is a
noteworthy fact that the cross-river portions are the driest parts of
the whole tunnels, -- and the subway is carried once under the River
Kelvin, as well as twice under the Clyde.

A drainage system had to be constructed to carry off the water that
must accumulate in all underground worings. For the section between
Partick and Cowcaddens, which one may call the northwestern segment of
the circle, a brick conduit was constructed, or 4 feet diameter, to run
the drainage into the River Kelvin. On the section between Cowcaddens
and Buchanan street, there is gravitation drainage into this conduit. On
the eastern side of Buchanan street station there is a fall to St. Enoch
station, where the water is pumped into the sewers.

On the south side of the river there is no natural outfall, and the
tunnels cannot be drained to one or two points to be there run off or
pumped up; there are, therefore, pumps at five different stations, the
most important of them being at Govan. The working of these pumps, in
order to keep the tunnels dry, means naturally a very large addition to
the running charges of the system, but as experience has been gained the
pumping is now better regulated,and will soon be done entirely by
electricity.

Although the use of the cable was in the original design sent to
Parliament, and was always favoured by Mr. Simpson and his partners, the
Subway Company was not confined to cable traction by their bill. They
were quite free to adopt any other mode of traction (except by steam
locomotives), and some of the promoters were strongly in favour of
electricity. It was, on the advice of Mr. David Home Morton, C. E., that
cable traction was finally decided on. Mr. Morton, on being appointed
consulting mechanical engineer to the company, addressed himself to a
practical and exhaustive study of all the systems of traction in use in
Europe and America, and found the balance of evidence distinctly in
favour of the cable in the peculiar conditions on which the subway must
work.

For electric traction the subway cars would have had to be made to
overcome the steep gradients, incomparably more heavy than there was
necessity for on the rest of the road. Then the circumference of the
tunnels limits the height of the cars, so that sufficiently powerful
motors could not be placed under them. This meant that electric
locomotives would have had to be employed, and that implied more heavy
rolling-stock and more heavy permanent way, and also more wear-and-tear.

By the cable system, on the other hand, the trains of cars, running
in opposite directions, assist one another,-- those going downhill
helping to pull those going uphill. By this principle of compensation
much hauling power is saved, and it becomes more effective as the number
of cars run is increased. Each additional electric car put on a route
means a large addition to the working expenses, but each addition to the
number of cars on the cable makes only a nominal demand on the
horsepower. Thus the service on the cable system can be increased as the
traffic requires, without appreciable increase of working expenses,
while on the electric system every car put in motion becomes a heavy
charge, whether it is earning money or not.

The cable system having been adopted, Mr. Morton proceeded to examine
carefully all the cable systems at work in America, and out of his long
and careful study of existing methods and machinery, he has evolved one
of the best and most perfectly equipped cable systems in the world.
While adopting every good idea he saw in use, Mr. Morton had to adapt,
alter, and invent as he went along with the equipment in the subway. He
had to contend with, or provide for, conditions which did not exist in
any of the systems elsewhere at work. The Glasgow District Subway, as it
is working today, is a striking monument of Mr. Morton's tireless
energy, mechanical genius, and unfailing resourcefulness. The whole
equipment was designed and constructed by him, and is still under his
supervision as consulting engineer of the company.

The adoption of the cable permitted of the use of comparatively light
rails on the track (60 pounds per yard), and of light rolling-stock. The
sleepers of the permanent way, which is of 4-foot gauge, are laid on
ballast, and the rails are spiked down to the sleepers without chairs.
The distance between the top of the rails and the highest point of the
roof of the tunnel is 9 1/2 feet.

The permanent way is so planned as to place every station at the
summit of a gradient of about 1 in 40, and this serves several good
purposes. Thus, the stations are brought more conveniently near the
surface; the up-grade assists the brakes in stopping the cars; and the
down-grade reduces the pull on the cable when a start is made, and
enables the start to be made smoothly and quickly. The cable is carried
over 1700 track-sheaves in each tunnel. On the straight track the
sheaves are vertical and 30 feet apart; on long curves they are
inclined; and on sharp curves they are horizontal.

On the sharpest curves both horizontal and inclined sheaves are used,
at distances of eight or nine feet,-- the distance apart increasing as the
curve widens. These sheaves, having to revolve at a very high speed, are
of special construction in each of the three types. They are all so
designed that when screwed down on the track they carry the cable at a
level of a couple of inches above the top of the rails. The cable is midway
between the rails in the straight track, but on curves is two or
three inches off the centre line, and towards the centre of the curve,
so as to prevent the "gripper" from fouling the inclined and
horizontal sheaves.

The cars, which were built by the Oldbury Carriage and Waggon
Company, are of the double bogie type of American pattern. Each ordinary
car weighs 9 tons, but trailer cars, slightly smaller and weighing 5
tons, are now attached, the two together forming a train with connecting
gangway. The interiors are roomy, with plenty of headroom (6 1/2 feet), and
with so much space between the longitudinal seats that you do not rub
against passengers' knees as you pass along.

The large cars are a trifle over 40 feet long, but a vestibule for
the driver at one end and one for the conductor at the other, reduce the
inside length to about 32 feet. These vestibules are shut off from the
car by glass-panelled sliding-doors, which are opened by the driver and
conductor when the car putls up at a platform. Passengers enter by the
rear door and leave by the door in the front. When the car starts the
vestibule doors are shut, and thus all draught in the interior is
prevented. The signal to start is given by the conductor to the driver
by means of an electric bell, and the side doors at each end, giving
access from the vestibules to the station platforms, are closed by iron
lattice-work. Entry and exit are easy, as the car floor is on a level
with the station platform. Both externally and internally the cars are
attractive in appearance. The interior fittings are of polished teak,
with oak panels; the roof is painted cream-coloured, relieved in gold
and vermilion; and the general effect is bright and fresh.

The inconvenience of noise, inseparable from cable running, is
reduced to a minimum by thick layers of felt, covered by linoleum, on
the floor, and by felt under the seats. There are windows all along the
sides and at the ends, although there is naturally not much to be seen
in a tunnel, and although there was a little trouble at the outset, the
cars are now admirably lighted by electricity on the trolley system.
That is to say, the current is picked up by means of trolley wheels from
two continuous conductors running along the side of each tunnel. There
is sitting room in each of the large cars for 48 persons, and ample
standing room for as many more without inconvenience to the sitters.

Though light, the cars are very strong, steel being largely used in
the construction. Bogies and underframing are of steel, and the
"gripper" is secured to the leading bogie under the leading axle. Between
the bogies and the car body are four sets of steel springs, but there
are no springs between the bogie and the axle boxes, so as to leave room
to keep the "gripper" clear of the track sheaves.

The gripper is, of course, the most important part of the car
equipment, and may be described, generally, as a powerful vice, secured
to the underframing, and operated by screws or levers, gripping the
cable in such a way as to impart its motion to the car. The subway
grippers differ from those used on the street cable lines, inasmuch as
the latter have to be dropped into the conduit below the surface, while
on the subway the cable runs above rail level, and the lowest part of
the gripper is several inches above the top of the rails. The gripper is
fixed parallel to the rails, under the forward axle of the leading
bogie, enabling it to travel on the centre line between the rails; the
bogie thus acts as a motor, guiding the long car.

Of the jaws, between which the cable is clamped, the lower is fixed,
while the upper can be raised or lowered at the will of the driver. The
cable, which must at times leave the gripper, can always be discharged
from one side. The jaws, being subject to considerable wear, are fitted
with renewable dies of rolled steel, giving effective lengths of 2 feet,
4 inches, and 2 feet, 9 inches, respectively, for top and bottom jaws.
The upper jaw is brought down on the rope by an arrangement of links and
levers, connected by chains to the driver's wheel in the forward
vestibule.

The gripper appears, at first sight, to be a very intricate piece of
mechanism. The apparent complication is, in reality, due to the
trip-gear for the discharge of the cable from the jaws and to the
duplication of levers, because of the unusual length of these jaws. The
tripgear consists of a very ingenious arrangement of links, pawls and
levers, whereby, even if the gripper is being held hard on by the
driver's handwheel, the top jaw can be suddenly released and allowed to
rise on springs clear of the cable, this act being followed by the
lifting of two small discharge bars, which, in turn, raise the cable and
throw it free of the gripper.

This gear is operated generally by means of a hand-lever by the
driver; but should he omit to use the lever at certain points where the
cable is to be released, a small roller on the forward end of the
gripper comes in contact with a long cam-bar fixed between the rails,
and causes the gear to act precisely as if the lever were used. At the
passenger stations the cable is not thrown out, but simply runs on the
lower die of the gripper, the top jaw being raised a little out of
contact.

The passenger stations are fifteen in number. A penny fare covers
four stations, and a twopenny fare covers the whole of either circuit.
The original intention was to have a universal penny fare and no
tickets, the fare to be paid at an automatic turnstile on entering a
station,-- and probably this design will be ultimately carried out. It
was, indeed, tried for a time, but was found to be abused by idle
persons, who, having once paid, went on round and round the circle,
either for the fun of the thing or for the pleasure of cheating the
company. It is a question whether the great saving to be effected by
dispensing with ticket-clerks and collectors would not more than
compensate for any loss in that way, which, though it might be
considerable when the thing was a novelty, is not likely to be much now
that the subway is thoroughly familiar.

Six of the subway stations are quite underground, and have to be
always electrically lighted; the others are open to daylight and have
glass roofs. All of them have island platforms, about 10 feet wide, on a
level with the car floors, and access to the street is by means of
stairs and corridors, lined with white tiles and electrically lighted.
At one station (Kelvinbridge) there is an electrically worked elevator
for the use of passengers between the street and the platform, and it is
intended that similar elevators will, in due time, be supplied at some
of the other stations.

So much, then, for the line and its equipment. The power station is
situated on the south side of the river, in a district of the city
chiefly given up to engineering. The main engine-house is 138 feet long,
100 feet wide, and 31 feet high from floor to roof. Heavy cast-iron
columns run down the centre to assist in carrying the girders for two
25-ton travelling cranes. The main engines are in duplicate, placed on
each side of the centre line of the enginehouse, but though one may be
used for each tunnel, it is found that one is sufficient for the traffic
in both tunnels. One engine, therefore, is always kept in reserve, and
the engines are run alternately, week or fortnight about.

Each engine is of the horizontal single-cylinder, non-condensing
type, with Corliss valves. The cylinder, which is steam jacketed, is 42
inches in diameter, and the piston has a stroke of 6 feet. The steam
inlet valves are actuated by means of an eccentric and rod independent
of those which work the exhaust valves, while, owing to the distance
from crank-shaft to valves, the eccentrics run on a counter shaft. The
ponderous flywheel, 25 feet in diameter, weighs 50 tons, being built up
of cast-iron hub, arms, and rim segments.

To give the maximum speed of 15 miles an hour to the cables, the
engine, which is capable of developing 1500 H. P. economically, runs at
55 revolutions per minute. Two governors are provided, the larger acting
on the valve gear, and the smaller on a throttle or butterfly valve
immediately above the main steam inlet valve. These two governors act
quite independently of each other. Midway between the two large engines
is a vertical, double-cylinder engine, 14 inches in diameter by 18
inches stroke, which serves as a barring engine to assist in starting
its big brothers. It is also of service for examining and repairing
cables and machinery, giving a slow, steady motion, either backward or
forward, under circumstances when the use of the big engine might be
attended with danger. In threading the first cables, this small engine
proved a valuable assistant.

Across the house runs the main driving-shaft, made in two lengths,
and ranging in diameter from 18 inches to 21 inches, with all the
necessary bearings and couplings arranged so that the shafting may be
run by either or both engines, or that in the event of one of the cables
having to be temporarily stopped, the other can be kept going. Running
loose on each section of this shaft is a 26-groove rope drum, 13 feet, 9
inches in diameter.

Power is transmitted to it by means of a Walker-Weston multiplate
friction clutch. This clutch consists of a series of annular plates,
which are attached alternately to a casing fixed to the drum and to a
sleeve fitted to and driven by the shaft. These plates are held by keys
so that they cannot revolve independently of the casing or the sleeve to
which they are attached, but all can slide to a certain extent parallel
to the axis of the shaft. To set the drum in motion it is only
necessary, by means of a hand-lever and rack and pinion arrangement, to
press all the annular plates together, causing great friction between
them.

The clutch-driven drum, in turn, drives two 25-foot diameter rope
drums, each of which is mounted on a separate shaft, one being 18 feet
in advance of the other. Of the twenty-six cotton driving ropes, which
are each 2 inches in diameter, fifteen drive the first drum. Owing to
the method of wrapping the steel cable on its driving-drums, the first,
of necessity, does more than the second, hence the cotton rope drum
which drives the second takes eleven ropes only.

A 14-foot diameter cable drum is fitted on the overhung end of each
of the 25-foot drum-shafts. These are differential drums of the Walker
type, with six grooves, and together drive one of the haulage cables.
They are set in line so that the bottoms of the grooves of one drum are
opposite to the ridges of the grooves on the other, to divide the angle
of divergence in wrapping the cable. A massive strut, with wedge
adjustment, between the shafts, counteracts the tendency of the cable to
bring the drum-shafts towards each other.

The Walker differential drum overcomes the difficulties ordinarily
experienced through the stretching and slipping of the cable and the
wearing of the grooves. Coming up from the road the cable runs up the
cable culvert to the under side of the differential drums, and after
taking the requisite number of turns around them, runs off to a 14-foot
sheave on the tension carriage, from which its direction is changed down
the culvert again to the road. The tension carriage can take up a
stretch of 300 feet.

The tension varies, of course, according to the number and position
of trains on the cable at a time, and an Upton tension regulator is
applied to meet the variation. This regulator consists of a variable
number of plate-weights, slung by four long links, two of which are
fixed to the anchorage, and two to a small four-wheeled carriage running
on the same rails as the tension carriage, and connected to it by means
of a wire rope. As the regulator carriage moves to and fro, owing to the
varying pull on the cable, the weights rise and fall, and their
effective value varies as the angularity of the links.

As the cable comes down the culvert on to the track it is diverted by
means of a 12-foot sheave, which is placed under the rails and slightly
out of the horizontal. From this 12-foot sheave the cable passes over
five 30-inch vertical sheaves, which are pretty close together, and
which elevate the cable about 7 inches above the rails, from which it
falls back to the normal working-level of 2 inches. On returning to the
station, of course, the operation is reversed, and the modus operandi is
the same for both tunnels, with the necessary difterence in deflection.

The boiler house equipment consists of eight Lancashire boilers, 8
feet in diameter and 30 feet long; but only four, or at most six, are
ever in use at one time. Boilers and fittings are constructed for a
pressure of 120 pounds per square inch, but the regular working pressure
is 100 pounds. Vicars mechanical stokers are used, and also a coal
elevator connecting with the stores beneath, power for these being
furnished by an 8 1/2 by 9-inch Robey high-speed engine. Over the boilers
there is a maze of pipes, all neatly clad in magnesia covering, painted
white. The whole place is scrupulously clean and bright.

The drudges of the system,-- the cables themselves,-- are well worth
attention. They are each 1 1/2 inches in diameter and 36,300 feet in
length, and are made up of six strands, of from 13 to 16 wires per
strand, laid on a hemp core Both the wires and the strands are laid from
left to right and not in opposite directions, as in the ordinary "lay,"
and thereby a greater wearing surface is presented. Each one of the
cables contains about 600 miles of steel wire, and when splicing is
necessary, a length of about 80 feet is taken for the splice. Splicing
is carefully taught in the yard, where old cables are kept for the
practice of the men, and rewards are given for proficiency in the art.

Each cable weighs about 57 tons, and one of the problems to be solved
was how to get such a weight transported from the cable makers' works in
the north of England to the power station. Each of the four makers who
have supplied cables has adopted a different method of transport, but
this is an interesting part of the story which hardly belongs to the
present purpose.

At the power station is also the electric plant for lighting the
whole of the line, and working pumps, elevators and other auxiliary
apparatus. It consists of four Silvertown continuous-current dynamos,
each coupled to a compound vertical Belliss engine with 9-inch
high-pressure and 15-inch low-pressure cylinders, the stroke being 9
inches. The dynamos are of the inverted horse-shoe type, and each is
capable of developing 79 kilowatts, or about 106 electric H. P.
Throughout, the wiring is done on the three-wire system.

The car shed is apart from the power station, and is situated near
the Govan Cross station of the subway. It is not the least interesting
feature of the system, for here is a most ingenious appliance for
lifting the cars bodily from, and for placing them onto, the track,
without stopping the cable or interrupting the traffic. The tunnels pass
right under the car shed, and access to them is through a shaft or pit,
55 feet long and 28 feet wide, and 20 feet deep, through which the cars
are lifted or lowered by means of a 12-ton travelling crane. This crane
acts both as an elevator, a turntable and a traverser,-- lifting the cars,
carrying them where required, turning them, and dropping them on to any
desired line of rails. The shed is 220 feet long and about 115 feet
broad, with a storage space of over 25,000 square feet.

Between the rails, on which the cars are placed when hoisted up from
the subway, are 3 foot pits, to permit of the inspection, cleaning and
repair of the under-frames and grippers. The cars cease running at 11 P.M.,
and as each completes its run, it is taken into the car shed for the
night. In case of damage or accident to any car on the circuit it can be
run (or if its own gripper is disabled, it can be pushed by the car
behind) to the car pit and there taken off the line without delaying the
traffic more than a moment.

Although the system is worked according to Board of Trade
regulations, on the block system, that system is practically automatic
and signalmen are dispensed with. At each station there is a semaphore,
at the end of each of the tunnels as it opens out into the arch. These
show red and green lights, which signify to the driver of the incoming
car whether the line in advance of him is clear or not. When the
preceding train has left the station in advance the starting signal is
given, and as soon as the train has gone its own length into the tunnel
it passes over a treadle which breaks the electric contact and sets the
signal behind at "danger," at which it must remain until the train,
on passing the next station, acts on another treadle, which releases the
danger signal and shows the line to be all clear between the two
stations.

The stations are also connected by telephones and electric bells, and
each station is also in communication with the power station, and can
signal for the stoppage of the engines there in case of need.
Practically, then, the "blocks" are the stations, and therefore the
frequency with which trains can be run is limited by the distance
between the blocks, as no train can leave a station until the train in
advance is starting from the next station.

At present the trains are run at intervals of three and a half
minutes, and this is about as close as they can get under the present
arrangement of blocks. A more frequent service, however, could be
maintained were the signals put midway in the tunnels between stations.
And here it may be mentioned that, although the Board of Trade insist
upon this blocking and signalling, many competent authorities think the
whole system unnecessary and unnecessarily expensive. It is argued that
the cars do not run at a rate of speed which would permit of any serious
accident, even if one did run into the rear of another. And they cannot
run into each other going in opposite directions. Each car is furnished
with such powerful head-lights that the driver can see a long way ahead,
and could always stop his own car before he could run into a disabled
one ahead.

In relation to the street tramways the subway is undoubtedly
handicapped. The working charges laid upon the subway (which do not fall
upon the street tramway) in respect of the Board of Trade regulations,
the blocking and signalling, and the limitation of trains by the block,
are very onerous. And then the subway has heavy special expenditure in
connection with lighting and pumping; while, being a novel undertaking,
the staffs in all departments are kept much larger, and therefore at
more expense, than there will be need for when every item in the system
has been thoroughly tested by experience. Yet with all these financial
drawbacks in comparison with competing systems, the subway is not only
paying, but promises to be a highly remunerative undertaking as traffic
increases and working expenses are reduced, as they are sure to be in
the near future.

As a means of locomotion the subway is comfortable, for the movement
of the cars is without spasmodic jerks, and the gradients are scarcely
felt. There is necessarily some noise from the running of the cable, but
it is minimised to something very much less than that on probably any
other underground railway. The steady weekly increase in the traffic
receipts may be taken as proof of the growing popularity, and therefore
efficiency, of the service.